The present invention relates to a method for shrink-proof treatment of a fabric material made of keratinous fibers or, in particular, woolen fibers. More particularly, the invention relates to a method for treating a woolen fabric material by which the fabric material can be imparted with excellent shrink resistance and softness in touch lastingly retained even after many times of repeated laundering.
Fabric materials of keratinous fibers or, typically, woolen fibers in general have a serious defect that the fabric material is subject to shrinkage when the fabric material is laundered or washed. This defect is due to the specific scaly surface structure of the fibers which causes intertwinement of the fibers resulting in felting of the fabric material. It is conventionally undertaken therefore that a woolen fabric material is subjected to a shrink-proof treatment and various methods have been proposed or attempted in the prior art.
For example, it is a well known method that the scaly surface structure of wool fibers can be smoothened by a treatment of a woolen fabric material with chlorine so as to decrease intertwinement of the fibers. This method, however, is not quite satisfactory because the effect of the chlorine treatment cannot be always very uniform and, in addition, yellowing sometimes takes place in the woolen fabric materials after chlorine treatment to greatly decrease the aesthetic value of beautiful color tone to be obtained by dyeing.
Alternatively, woolen fabric materials are treated with a certain urethane resin so that the scaly surface of the woolen fibers is coated with a coating layer of the resin to be smoothened resulting in a decrease in the shrinkage of the fabric material by laundering. This method, however, has a problem that the softness of the fabric material as a feature inherent in wool products is greatly decreased and the fabric material is stiffened by the treatment.
Despite the problems above mentioned, these methods are widely practiced in the industry of wool products because the shrink-proof effect obtained by these methods is high enough and, in particular, the effect is durable to be retained even after repeated laundering.
With an object to obtain a shrink-proof effect of woolen fabric materials without a decrease in the soft feeling of touch of the fabric material, proposals have been made for the shrink-proof treatment of woolen fabric materials with a silicone-based shrink-proof agent. Methods by using various types of silicone-based shrink-proof agents are known in the prior art including a method by using a composition comprising a solution of an organopolysiloxane of a straightly linear molecular structure terminated at each molecular chain end with a silanolic hydroxy group and having a viscosity of at least 50 centistokes at 25.degree. C. and a methyl hydrogen polysiloxane dissolved in an organic solvent with admixture of a curing catalyst as is disclosed in Japanese Patent Publication 48-33435, a method in which the silicone-based shrink-proof agent is a composition comprising a diorganopolysiloxane having amino groups and alkoxy groups in a molecule as is disclosed in Japanese Patent Publication 53-28468, a method in which the silicone-based shrink-proof agent is a composition comprising an organopolysiloxane having amino groups and mercapto groups in a molecule as is disclosed in Japanese Patent Publication 58 -4114, and so on.
At any rate, these prior art methods by using a silicone-based shrink-proof agent are not always quite satisfactory in respect of the durability of the shrink-proof effect even though a high shrink-proof effect can be obtained directly after the treatment. Namely, the shrink-proof effect imparted to the fabric material by the treatment is rapidly lost by repeating laundering. In addition, the woolen fabric material treated with these silicone-based shrink-proof agents is disadvantageous because of the loss of the soft and pleasant feeling of touch as a result of the silicone treatment.
An improved method is disclosed recently in Japanese Patent Kokai 2-84579 according to which the fibers of a woolen fabric material are subjected to surface oxidation by the treatment with chlorine followed by the treatment of surface coating with an amino-modified silicone resin. This method indeed is effective to a considerable extent to solve the above described problems in the shrink-proof treatment of woolen fabric materials though far from satisfactory.
Thus, it is eagerly desired to develop a reliable method for the shrink-proof treatment of a woolen fabric material capable of imparting the fabric material with highly laundering-resistant shrink-proofness and very pleasant soft feeling of touch without causing yellowing.